include/sim/callback.h

   1 /* Remote target system call callback support.
   2    Copyright (C) 1997-2021 Free Software Foundation, Inc.
   3    Contributed by Cygnus Solutions.
   4
   5    This file is part of GDB.
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 3 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  19
  20 /* This interface isn't intended to be specific to any particular kind
  21    of remote (hardware, simulator, whatever).  As such, support for it
  22    (e.g. sim/common/callback.c) should *not* live in the simulator source
  23    tree, nor should it live in the gdb source tree.  */
  24
  25 /* There are various ways to handle system calls:
  26
  27    1) Have a simulator intercept the appropriate trap instruction and
  28    directly perform the system call on behalf of the target program.
  29    This is the typical way of handling system calls for embedded targets.
  30    [Handling system calls for embedded targets isn't that much of an
  31    oxymoron as running compiler testsuites make use of the capability.]
  32
  33    This method of system call handling is done when STATE_ENVIRONMENT
  34    is ENVIRONMENT_USER.
  35
  36    2) Have a simulator emulate the hardware as much as possible.
  37    If the program running on the real hardware communicates with some sort
  38    of target manager, one would want to be able to run this program on the
  39    simulator as well.
  40
  41    This method of system call handling is done when STATE_ENVIRONMENT
  42    is ENVIRONMENT_OPERATING.
  43 */
  44
  45 #ifndef SIM_CALLBACK_H
  46 #define SIM_CALLBACK_H
  47
  48 #include <ansidecl.h>
  49 #include <stdarg.h>
  50 #include <stdint.h>
  51 /* Needed for enum bfd_endian.  */
  52 #include "bfd.h"
  53 \f
  54 /* Mapping of host/target values.  */
  55 /* ??? For debugging purposes, one might want to add a string of the
  56    name of the symbol.  */
  57
  58 typedef struct {
  59   const char *name;
  60   int host_val;
  61   int target_val;
  62 } CB_TARGET_DEFS_MAP;
  63
  64 #define MAX_CALLBACK_FDS 10
  65
  66 /* Forward decl for stat/fstat.  */
  67 struct stat;
  68
  69 typedef struct host_callback_struct host_callback;
  70
  71 struct host_callback_struct
  72 {
  73   int (*close) (host_callback *,int);
  74   int (*get_errno) (host_callback *);
  75   int (*isatty) (host_callback *, int);
  76   int64_t (*lseek) (host_callback *, int, int64_t, int);
  77   int (*open) (host_callback *, const char*, int mode);
  78   int (*read) (host_callback *,int,  char *, int);
  79   int (*read_stdin) ( host_callback *, char *, int);
  80   int (*rename) (host_callback *, const char *, const char *);
  81   int (*system) (host_callback *, const char *);
  82   int64_t (*time) (host_callback *);
  83   int (*unlink) (host_callback *, const char *);
  84   int (*write) (host_callback *,int, const char *, int);
  85   int (*write_stdout) (host_callback *, const char *, int);
  86   void (*flush_stdout) (host_callback *);
  87   int (*write_stderr) (host_callback *, const char *, int);
  88   void (*flush_stderr) (host_callback *);
  89   int (*to_stat) (host_callback *, const char *, struct stat *);
  90   int (*to_fstat) (host_callback *, int, struct stat *);
  91   int (*to_lstat) (host_callback *, const char *, struct stat *);
  92   int (*ftruncate) (host_callback *, int, int64_t);
  93   int (*truncate) (host_callback *, const char *, int64_t);
  94   int (*getpid) (host_callback *);
  95   int (*pipe) (host_callback *, int *);
  96
  97   /* Called by the framework when a read call has emptied a pipe buffer.  */
  98   void (*pipe_empty) (host_callback *, int read_fd, int write_fd);
  99
 100   /* Called by the framework when a write call makes a pipe buffer
 101      non-empty.  */
 102   void (*pipe_nonempty) (host_callback *, int read_fd, int write_fd);
 103
 104   /* When present, call to the client to give it the oportunity to
 105      poll any io devices for a request to quit (indicated by a nonzero
 106      return value). */
 107   int (*poll_quit) (host_callback *);
 108
 109   /* Used when the target has gone away, so we can close open
 110      handles and free memory etc etc.  */
 111   int (*shutdown) (host_callback *);
 112   int (*init)     (host_callback *);
 113
 114   /* depreciated, use vprintf_filtered - Talk to the user on a console.  */
 115   void (*printf_filtered) (host_callback *, const char *, ...);
 116
 117   /* Talk to the user on a console.  */
 118   void (*vprintf_filtered) (host_callback *, const char *, va_list);
 119
 120   /* Same as vprintf_filtered but to stderr.  */
 121   void (*evprintf_filtered) (host_callback *, const char *, va_list);
 122
 123   /* Print an error message and "exit".
 124      In the case of gdb "exiting" means doing a longjmp back to the main
 125      command loop.  */
 126   void (*error) (host_callback *, const char *, ...) ATTRIBUTE_NORETURN;
 127
 128   int last_errno;               /* host format */
 129
 130   int fdmap[MAX_CALLBACK_FDS];
 131   /* fd_buddy is used to contruct circular lists of target fds that point to
 132      the same host fd.  A uniquely mapped fd points to itself; for a closed
 133      one, fd_buddy has the value -1.  The host file descriptors for stdin /
 134      stdout / stderr are never closed by the simulators, so they are put
 135      in a special fd_buddy circular list which also has MAX_CALLBACK_FDS
 136      as a member.  */
 137   /* ??? We don't have a callback entry for dup, although it is trival to
 138      implement now.  */
 139   short fd_buddy[MAX_CALLBACK_FDS+1];
 140
 141   /* 0 = none, >0 = reader (index of writer),
 142      <0 = writer (negative index of reader).
 143      If abs (ispipe[N]) == N, then N is an end of a pipe whose other
 144      end is closed.  */
 145   short ispipe[MAX_CALLBACK_FDS];
 146
 147   /* A writer stores the buffer at its index.  Consecutive writes
 148      realloc the buffer and add to the size.  The reader indicates the
 149      read part in its .size, until it has consumed it all, at which
 150      point it deallocates the buffer and zeroes out both sizes.  */
 151   struct pipe_write_buffer
 152   {
 153     int size;
 154     char *buffer;
 155   } pipe_buffer[MAX_CALLBACK_FDS];
 156
 157   /* System call numbers.  */
 158   CB_TARGET_DEFS_MAP *syscall_map;
 159   /* Errno values.  */
 160   CB_TARGET_DEFS_MAP *errno_map;
 161   /* Flags to the open system call.  */
 162   CB_TARGET_DEFS_MAP *open_map;
 163   /* Signal numbers.  */
 164   CB_TARGET_DEFS_MAP *signal_map;
 165   /* Layout of `stat' struct.
 166      The format is a series of "name,length" pairs separated by colons.
 167      Empty space is indicated with a `name' of "space".
 168      All padding must be explicitly mentioned.
 169      Lengths are in bytes.  If this needs to be extended to bits,
 170      use "name.bits".
 171      Example: "st_dev,4:st_ino,4:st_mode,4:..."  */
 172   const char *stat_map;
 173
 174   enum bfd_endian target_endian;
 175
 176   /* Size of an "int" on the target (for syscalls whose ABI uses "int").
 177      This must include padding, and only padding-at-higher-address is
 178      supported.  For example, a 64-bit target with 32-bit int:s which
 179      are padded to 64 bits when in an array, should supposedly set this
 180      to 8.  The default is 4 which matches ILP32 targets and 64-bit
 181      targets with 32-bit ints and no padding.  */
 182   int target_sizeof_int;
 183
 184   /* Marker for those wanting to do sanity checks.
 185      This should remain the last member of this struct to help catch
 186      miscompilation errors. */
 187 #define HOST_CALLBACK_MAGIC 4705 /* teds constant */
 188   int magic;
 189 };
 190
 191 extern host_callback default_callback;
 192 \f
 193 /* Canonical versions of system call numbers.
 194    It's not intended to willy-nilly throw every system call ever heard
 195    of in here.  Only include those that have an important use.
 196    ??? One can certainly start a discussion over the ones that are currently
 197    here, but that will always be true.  */
 198
 199 /* These are used by the ANSI C support of libc.  */
 200 #define CB_SYS_exit     1
 201 #define CB_SYS_open     2
 202 #define CB_SYS_close    3
 203 #define CB_SYS_read     4
 204 #define CB_SYS_write    5
 205 #define CB_SYS_lseek    6
 206 #define CB_SYS_unlink   7
 207 #define CB_SYS_getpid   8
 208 #define CB_SYS_kill     9
 209 #define CB_SYS_fstat    10
 210 /*#define CB_SYS_sbrk   11 - not currently a system call, but reserved.  */
 211
 212 /* ARGV support.  */
 213 #define CB_SYS_argvlen  12
 214 #define CB_SYS_argv     13
 215
 216 /* These are extras added for one reason or another.  */
 217 #define CB_SYS_chdir    14
 218 #define CB_SYS_stat     15
 219 #define CB_SYS_chmod    16
 220 #define CB_SYS_utime    17
 221 #define CB_SYS_time     18
 222
 223 /* More standard syscalls.  */
 224 #define CB_SYS_lstat    19
 225 #define CB_SYS_rename   20
 226 #define CB_SYS_truncate 21
 227 #define CB_SYS_ftruncate 22
 228 #define CB_SYS_pipe     23
 229
 230 /* New ARGV support.  */
 231 #define CB_SYS_argc     24
 232 #define CB_SYS_argnlen  25
 233 #define CB_SYS_argn     26
 234 \f
 235 /* Struct use to pass and return information necessary to perform a
 236    system call.  */
 237 /* FIXME: Need to consider target word size.  */
 238
 239 typedef struct cb_syscall {
 240   /* The target's value of what system call to perform.  */
 241   int func;
 242   /* The arguments to the syscall.  */
 243   long arg1, arg2, arg3, arg4;
 244
 245   /* The result.  */
 246   long result;
 247   /* Some system calls have two results.  */
 248   long result2;
 249   /* The target's errno value, or 0 if success.
 250      This is converted to the target's value with host_to_target_errno.  */
 251   int errcode;
 252
 253   /* Working space to be used by memory read/write callbacks.  */
 254   void *p1;
 255   void *p2;
 256   long x1,x2;
 257
 258   /* Callbacks for reading/writing memory (e.g. for read/write syscalls).
 259      ??? long or unsigned long might be better to use for the `count'
 260      argument here.  We mimic sim_{read,write} for now.  Be careful to
 261      test any changes with -Wall -Werror, mixed signed comparisons
 262      will get you.  */
 263   int (*read_mem) (host_callback * /*cb*/, struct cb_syscall * /*sc*/,
 264                    unsigned long /*taddr*/, char * /*buf*/,
 265                    int /*bytes*/);
 266   int (*write_mem) (host_callback * /*cb*/, struct cb_syscall * /*sc*/,
 267                     unsigned long /*taddr*/, const char * /*buf*/,
 268                     int /*bytes*/);
 269
 270   /* For sanity checking, should be last entry.  */
 271   int magic;
 272 } CB_SYSCALL;
 273
 274 /* Magic number sanity checker.  */
 275 #define CB_SYSCALL_MAGIC 0x12344321
 276
 277 /* Macro to initialize CB_SYSCALL.  Called first, before filling in
 278    any fields.  */
 279 #define CB_SYSCALL_INIT(sc) \
 280 do { \
 281   memset ((sc), 0, sizeof (*(sc))); \
 282   (sc)->magic = CB_SYSCALL_MAGIC; \
 283 } while (0)
 284 \f
 285 /* Return codes for various interface routines.  */
 286
 287 typedef enum {
 288   CB_RC_OK = 0,
 289   /* generic error */
 290   CB_RC_ERR,
 291   /* either file not found or no read access */
 292   CB_RC_ACCESS,
 293   CB_RC_NO_MEM
 294 } CB_RC;
 295
 296 /* Read in target values for system call numbers, errno values, signals.  */
 297 CB_RC cb_read_target_syscall_maps (host_callback *, const char *);
 298
 299 /* Translate target to host syscall function numbers.  */
 300 int cb_target_to_host_syscall (host_callback *, int);
 301
 302 /* Translate host to target errno value.  */
 303 int cb_host_to_target_errno (host_callback *, int);
 304
 305 /* Translate target to host open flags.  */
 306 int cb_target_to_host_open (host_callback *, int);
 307
 308 /* Translate target signal number to host.  */
 309 int cb_target_to_host_signal (host_callback *, int);
 310
 311 /* Translate host signal number to target.  */
 312 int cb_host_to_gdb_signal (host_callback *, int);
 313
 314 /* Translate symbols into human readable strings.  */
 315 const char *cb_host_str_syscall (host_callback *, int);
 316 const char *cb_host_str_errno (host_callback *, int);
 317 const char *cb_host_str_signal (host_callback *, int);
 318 const char *cb_target_str_syscall (host_callback *, int);
 319 const char *cb_target_str_errno (host_callback *, int);
 320 const char *cb_target_str_signal (host_callback *, int);
 321
 322 /* Translate host stat struct to target.
 323    If stat struct ptr is NULL, just compute target stat struct size.
 324    Result is size of target stat struct or 0 if error.  */
 325 int cb_host_to_target_stat (host_callback *, const struct stat *, void *);
 326
 327 /* Translate a value to target endian.  */
 328 void cb_store_target_endian (host_callback *, char *, int, long);
 329
 330 /* Tests for special fds.  */
 331 int cb_is_stdin (host_callback *, int);
 332 int cb_is_stdout (host_callback *, int);
 333 int cb_is_stderr (host_callback *, int);
 334
 335 /* Read a string out of the target.  */
 336 int cb_get_string (host_callback *, CB_SYSCALL *, char *, int, unsigned long);
 337
 338 /* Perform a system call.  */
 339 CB_RC cb_syscall (host_callback *, CB_SYSCALL *);
 340
 341 #endif